
/*
 * Copyright 2002-2023 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 *版权所有2002-2023原作者。
 *
 *根据Apache许可证2.0版（“许可证”）许可；
 *除非符合许可证的规定，否则您不得使用此文件。
 *您可以在以下网址获取许可证副本
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 *除非适用法律要求或书面同意，否则软件
 *根据许可证分发是在“按原样”的基础上分发的，
 *无任何明示或暗示的保证或条件。
 *有关管理权限的特定语言，请参阅许可证
 *许可证下的限制。
 */

package org.springframework.context;

import java.util.EventListener;
import java.util.function.Consumer;

/**
 * Interface to be implemented by application event listeners.
 *
 * <p>Based on the standard {@link java.util.EventListener} interface for the
 * Observer design pattern.
 *
 * <p>An {@code ApplicationListener} can generically declare the event type that
 * it is interested in. When registered with a Spring {@code ApplicationContext},
 * events will be filtered accordingly, with the listener getting invoked for
 * matching event objects only.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @param <E> the specific {@code ApplicationEvent} subclass to listen to
 * @see org.springframework.context.ApplicationEvent
 * @see org.springframework.context.event.ApplicationEventMulticaster
 * @see org.springframework.context.event.SmartApplicationListener
 * @see org.springframework.context.event.GenericApplicationListener
 * @see org.springframework.context.event.EventListener
 */
/**
 *要由应用程序事件侦听器实现的接口。
 *
 *＜p＞基于
 *观察者设计模式。
 *
 *＜p＞｛@code ApplicationListener｝可以一般性地声明
 *当向Spring｛@code ApplicationContext｝注册时，
 *事件将被相应地过滤，侦听器将被调用
 *仅匹配事件对象。
 *
 *@作者罗德·约翰逊
 *@作者Juergen Hoeller
 *@param＜E＞要侦听的特定｛@code ApplicationEvent｝子类
 *@参见org.springframework.context.ApplicationEvent
 *@参见org.springframework.context.event.ApplicationEventMultimaster
 *@参见org.springframework.context.event.SmartApplicationListener
 *@参见org.springframework.context.event.GenericApplicationListener
 *@参见org.springframework.context.event.EventListener
 */
@FunctionalInterface
public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {

	/**
	 * Handle an application event.
	 * @param event the event to respond to
	 */
	/**
	 *处理应用程序事件。
	 *@param event要响应的事件
	 */
	void onApplicationEvent(E event);


	/**
	 * Create a new {@code ApplicationListener} for the given payload consumer.
	 * @param consumer the event payload consumer
	 * @param <T> the type of the event payload
	 * @return a corresponding {@code ApplicationListener} instance
	 * @since 5.3
	 * @see PayloadApplicationEvent
	 */
	/**
	 *为给定的负载使用者创建一个新的{@code ApplicationListener}。
	 *@param consumer事件负载消费者
	 *@param＜T＞事件负载的类型
	 *@返回对应的{@code ApplicationListener}实例
	 *@自5.3起
	 *@请参阅PayloadApplicationEvent
	 */
	static <T> ApplicationListener<PayloadApplicationEvent<T>> forPayload(Consumer<T> consumer) {
		return event -> consumer.accept(event.getPayload());
	}

}
